Method and apparatus for manufacturing a cell stack for battery cells

ABSTRACT

A method for producing a cell stack for battery cells comprises at least the following steps: feeding in at least a first material strip consisting of a first material; making a first cut into at least the first material strip while forming at least one transport section having tensile strength; combining the first material strip with at least a second material strip consisting of a second material, so as to form a partial stack; making a second cut of the partial stack, whereby the transport section is cut open; and arranging at least two partial stacks so as to form a cell stack.

FIELD OF THE INVENTION

The present invention relates to a method and to a device for producinga cell stack for battery cells.

BACKGROUND OF THE INVENTION

It is a known procedure from the state of the art to produce cell stacksfor battery cells in that individual installations are used toindividuate cathode sheets, anode sheets and separator sheets. Thesheets produced in this manner are then each delivered individually andseparately in magazines and positioned and aligned individually withinthe scope of an individual sheet stacking procedure during the formationof the stack. This process for producing a cell stack requires very highcycle times.

Another known method is so-called accordion folding in which a separatorsheet is wrapped around individual electrode sheets, but these sheetslikewise have to be first individuated and positioned in a precedingprocess step. It is also the case that accordion folding allows onlyrelatively slow cycle times.

Moreover, it is a known procedure to form stacks by means of alamination process. In order to achieve this, however, the cathodesheets and the anode sheets have to be laminated with separator films.However, the lamination-capable separator films needed for this purposeare relatively expensive.

The prior-art concepts entail various drawbacks. For instance, cellstack formation is currently a very slow process within the scope of theproduction of battery cells. Moreover, retaining the requisite positiontolerances is currently extremely difficult to achieve during the stackformation process at short cycle times. Furthermore, separatelypreparing individual sheets for the cell stack, subsequently placingthem into magazines, combining them, stacking them and joining themrequires several process steps that each involve complicated handling ofthe material. The large number of process steps also calls for a greatercomplexity of the plant technology and only relatively slow cycle timescan be attained.

SUMMARY OF THE INVENTION

Consequently, the objective of the present invention is to at leastpartially overcome the problems that arise from the state of the art. Inparticular, a method and a device are to be put forward with which acell stack for battery cells can be produced very quickly. Moreover, thepositioning accuracy of the material strips that are employed is to beimproved and the complexity of the plant technology is to be reduced.

A method having the features of patent claim 1 contributes towardsachieving these objectives. Advantageous refinements are the subjectmatter of the dependent patent claims. The features presentedindividually in the patent claims can be combined with each other in atechnically meaningful manner and can be augmented by elucidating factsfrom the description and/or by details from the figures, whereby otherembodiment variants of the invention are presented.

A method for producing a cell stack for battery cells is being proposedhere, said method comprising at least the following steps:

-   a) feeding in at least a first material strip comprising a first    material;-   b) making a first cut into at least the first material strip while    forming at least one transport section having tensile strength;-   c) combining the first material strip with at least a second    material strip consisting of a second material, so as to form a    partial stack;-   d) making a second cut of the partial stack, whereby the transport    section is cut open;-   e) arranging at least two partial stacks so as to form a cell stack.

Steps a) to e) can be carried out at least once in the sequence shownhere, namely, a), b), c), d) and e). It is possible for these steps tobe carried out a different number of times and/or at least partiallyoverlapping in time.

In this process, initially at least a material strip with a firstmaterial is fed in. The material strip can be selected, for example, foruse as an anode, as a cathode or as a separator of a battery cell. Here,for an anode, a suitable substrate, for example, is one that is made ofa material containing copper and that has an anode active layer appliedonto it. Accordingly, for example, a material containing aluminum issuitable as the substrate for a cathode active layer applied onto it.Flexible microporous plastics or nonwovens, for instance, are options asseparators.

The material strips can preferably be fed by supply means such as, forexample, rolls or coils having large strip lengths, so that continuous,uninterrupted operation of the method is possible over a prolongedperiod of time.

For example, if a first material strip that is suitable for producing ananode is fed in, this strip can undergo a first cut by a first cuttingdevice, whereby the cut is made in such a way that at least onetransport section having tensile strength remains. In this context, thetransport section should be configured such that it can absorb tensileforces in a lengthwise direction of the material strip. This makes itpossible to process the material strip as a continuous material strip inthe subsequent steps, since the forces needed for the further transportcan be introduced into the transport section.

In a particularly simple embodiment of the invention, the first materialstrip that has been cut this way is then simply combined with a secondmaterial strip, for example, with a separator, in order to form apartial stack. In particular, the second material strip of the separatoris also kept ready in a supply means, for example, as a separator coil,so that the process of making the first cut and combining the first andsecond material strips can be carried out at high speed.

After the combining step, the partial stack is then fed to a second cut,for which purpose the transport section once again serves as the pointof attack for the drive forces.

The second cut of the partial stack can then be made by a second cuttingdevice, whereby the transport section is separated from the partialstack and a separation is effectuated by means of a division of thepartial stack in the transversal direction relative to the direction ofmovement of the partial stack.

The two-layered partial stack that has been formed and separated in thismanner then has an anode and a separator. These partial stacks can thenbe arranged so as to form a cell stack.

In particular, it can be provided that the first material strip and thesecond material strip can be cut to different dimensions. With an eyetowards the safety of battery cells, separators have to protrude in alldirections and to a sufficient extent beyond the anodes and cathodesthat are to be insulated in order to reliably prevent a flow of currentbetween these two material strips. Here, an oversize of the separatorshould extend all around beyond a cathode by approximately 3 mm andbeyond an anode by approximately 1.5 mm. This means, for example, thatthe separator should be about 6 mm larger than the cathode and about 3mm larger than the anode.

These different sizes can preferably already be created within the scopeof the first cut by means of the first cutting devices that make anindividual cut for each material strip. For this purpose, for example,the cathode is cut to the desired width relative to the width of therequisite transport section. At the same time, the anode is cut to thedesired width plus an oversize of 3 mm and plus the width of thetransport section. Finally, the separator is cut to the desired widthplus an oversize of 6 mm. It should be noted here that transversal cutscan also already have been made in all three material strips. The onlyimportant aspect here is that at least one transport section always hasto be retained that is suitable to absorb and transmit tensile forcesthat are acting in the lengthwise direction of the material strips. Whenthe material strips are properly aligned laterally relative to eachother, they can be combined and fed to the second cutting device for thesecond cut, so as to then yield individuated partial stacks that can bestacked on top of each other.

Especially advantageously, during the cut, a transport engagement meansor a window section is created in the material strip, especially in thetransport section. This is preferably already done during the first cutin that, for example, small windows or perforations are made in thematerial strip, and drives with pins, drive wheels or the like that areused for the further transport can later engage with these windows orperforations.

The partial stacks can especially consist of at least four materialstrips. Here, particularly the combination of material strips in theform of two electrodes and two separators is advantageous. When possiblecombinations are made of these material strips, then the partial stacksmade from them can be arranged on top of each other up to the requiredheight of the cell stack, where it is then merely necessary to add aseparator as the first or last material strip.

If the combination of an anode, a separator, a cathode, and a separatorarranged on top of each other is selected, then a single separator hasto be put in place when the partial stack starts to be arranged, sinceotherwise the bottom anode would not be insulated.

If instead, the combination is a separator, an anode, a separator, and acathode arranged on top of each other, then a single separator has to beput in place when the arranging of the partial stack has been completed,since otherwise the top cathode would not be insulated.

In particular, arrester lugs can already be formed on at least twomaterial strips during the cutting. This lends itself especially in thecase of the material strips of the anodes and cathodes. Here, thearresters can be formed completely and without additional work duringthe first and second cuts by simply selecting an appropriate andsuitable cut contour.

In particular, in an immediately subsequent method step, the cell stackproduced according to the present method can be joined to form a cellpacket using a joining means such as, for example, an adhesive strip ortape. This additional step is very easy to add to the present method.

When it comes to the automatic arranging, it is especially advantageousif at least one additional material strip is arranged in the cell stackwhile the partial packets are being arranged to form the cell stack. Asalready described above, this material strip can be inserted into thecell stack, either at the bottom of the cell packet and thus at thebeginning of the arranging of the partial stack or else at the top ofthe cell packet and thus at the end of the arranging of the partialstack.

A battery cell having a cell stack, produced according to one of thepreceding claims, has the advantage that it can be producedcost-effectively, and thanks to the automated and continuous processing,individual material strips are arranged with good positioning accuracyrelative to each other. This lowers the costs and increases the servicelife and reliability of the battery cell.

This also applies especially to a motor vehicle having at least onebattery cell according to the preceding claim.

The device for producing a cell stack, which is also being proposed bythe invention, comprises at least two supply means for at least a firstmaterial strip and a second material strip, at least a first cuttingdevice and a second cutting device for cutting the material, and atransport means for conveying the material strips, an apparatus forcombining the material strips as well as a stacking unit, whereby thefirst cutting device creates at least one strip-like transport sectionhaving tensile strength, whereby the second cutting device is arrangedin a lengthwise direction downstream from the apparatus for combiningthe material strips, and said second cutting device is configured tomake a completely transversal separation of the material strips. As seenin the lengthwise direction, the transport section is preferably formedon the outer edge of the material strip and it has a width of less than25% of the width of the material strip. In actual practice, widths inthe range from 2 mm to 30 mm can already be totally adequate. If severaltransport sections are provided on different material strips, then theypreferably have to be arranged relative to each other so as to betransversally offset to the lengthwise direction, so that, for example,drive means—independently of each other—can be made to engage with thesetransport sections. As an alternative, a drive means can alsosimultaneously engage with several transport sections and thus ensure asynchronous transport of several material strips.

In particular, the first cutting device can be configured to undertakeparallel cutting of at least two material strips.

Moreover, it can be provided for the first cutting device to beconfigured to cut at least one material strip parallel to the lengthwisedirection in a plurality of material strips. As a result, it is alsopossible to process wider material strips, for example, in the firstcutting device. Here, the desired first cut is preferably madeinitially, and then the material strip is divided so as to acquire therequisite width. Thus, for example, material strips for separators canbe cut that have twice the width of the required separator. If, duringthe first cut, this wide material strip is now divided into two materialstrips of separators, then these two material strips can be continuouslyand uninterruptedly further processed immediately within the scope of apartial stack comprising two electrodes and two separators.

For the sake of clarity, it should be pointed out that the numerals usedhere (“first”, “second”, etc.) serve primarily (only) to differentiateamong several similar objects, dimensions or processes, in other words,they especially do not necessarily prescribe a dependence and/orsequence of these objects, dimensions or processes relative to eachother. If such a dependence and/or sequence is/are necessary, this isexplicitly pointed out here or else it is obvious to the person skilledin the art upon studying the concretely described embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention as well as the technical field will be explained ingreater detail below on the basis of the accompanying figures. It shouldbe pointed out that the invention is not restricted to the embodimentspresented. In particular, unless not explicitly indicated otherwise, itis also possible for partial aspects of the facts elaborated upon in thefigures to be extracted and to be combined with other components andinsights stemming from the present description. In particular, it shouldbe mentioned that the figures and especially the size ratios presentedare only of a schematic nature. The following is shown:

FIG. 1: a side sectional view of a first cutting device for an anode;

FIG. 2: a top view of the cutting device shown in FIG. 1;

FIG. 3: a top view of an anode after the first cut;

FIG. 4: a top view of a cathode after the first cut;

FIG. 5: a side sectional view of a first cutting device for a separator;

FIG. 6: a top view of two conceivable cuts for a separator;

FIG. 7: a conceivable combination of four strips of material;

FIG. 8: a side view of the process from the point in time when thestrips of material were combined;

FIG. 9: a top view of four combined strips of material;

FIG. 10: the gripping manner of the first clamping apparatus;

FIG. 11: the closing of the first clamping apparatus;

FIG. 12: the gripping manner of the second clamping apparatus;

FIG. 13: the closing of the second clamping apparatus;

FIG. 14: a side view of a cam drive;

FIG. 15: a sectional depiction through a cam wheel of a cam drive;

FIG. 16: a top view and a side view with a first, second and thirdclamping apparatus;

FIG. 17: a top view of a second cutting device;

FIG. 18: a diagonal view of a first roller of a second cutting device;

FIG. 19: a side view of a second cutting device;

FIG. 20: a top view and a side view with a second cutting device and twomagazines;

FIG. 21: a side view of the third clamping apparatus, the gripping meansand a magazine;

FIG. 22: a top view of a conveyor belt with a finished and an unfinishedcell packet;

FIG. 23: a side view of a first step for gluing the cell stack;

FIG. 24: a side view of a second step for gluing the cell stack;

FIG. 25: a side view of a third step for gluing the cell stack;

FIG. 26: a side view of a fourth step for gluing the cell stack;

FIG. 27: a side view of the placement of a cell packet on the conveyorbelt;

FIG. 28: a top view of a finished cell packet; and

FIG. 29: an alternative embodiment of a second cutting device.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a first cutting device 1 in a side view. On the left-handside of FIG. 1, there is a first supply means 2 that contains a supplyof a first material strip 3. The first supply means 2 can be, forinstance, a pre-manufactured unit comprising a calendered mother coilwith a first material strip 3, for example, for an anode 7 of a batterycell 8. The calendered first material strip 3—which has been rolled upinto a coil—has a highly uniform layer thickness and is fed to the firstcutting device 1 at the most constant and defined tensile forcespossible in order to avoid creasing in the first material strip 3. Thefirst cutting device 1 consists of a bottom roller 4, a top roller 5 aswell as well as a perforating unit 6. The cut made in the first cuttingdevice 1 will be elaborated upon below. In the embodiment shown here,the first material strip 3 has a width that has been selected in such away that the material strip 3 can be divided in the lengthwise directionduring the cut, so that two first material strips 3 a, 3 b aresimultaneously created in the first cutting device 1 and they can thensubsequently be further processed. As an alternative to the embodimentshown here, in which the first material strip 3 has a width thatcorresponds to twice the width of a first material strip 3 a, 3 b thathas been cut to size, however, it is also easily possible to use a firstmaterial strip 3 that corresponds to the single width or multiple widthsof the first material strip 3 a, 3 b that has been cut. In the lattercase, a corresponding number of separating cuts would have to be made inthe lengthwise direction of the material strip 3. For purposes of makingthe cut, the bottom roller 4 can be made, for example, of a hardenedmaterial such as, for instance, tungsten carbide or chromium steel. Theperforating unit 6 is configured in the form of a punch that is suitablefor punching holes into the appertaining divided first material strip 3a, 3 b.

FIG. 2 depicts a top view of the first cutting device 1 shown in FIG. 1.Starting from the first supply means 2, which is arranged on theleft-hand side, the first material strip 3 is fed towards the right tothe depicted bottom roller 4. The first material strip 3 has an anodearea 9 and an edge 10. The anode area 9 is coated with a material thatis suitable for later utilization as the anode 7 in a battery cell 8,namely, a so-called anode active layer. The substrate of the anode ispreferably a copper material. In this context, it can be clearly seenthat the first material strip 3 is twice as wide as the first materialstrips 3 a, 3 b after the first cut. The bottom roller 4 has a rotaryblade 11 that creates a longitudinal cut 12 in the middle of thematerial strip 3. Subsequently, the perforating unit 6 creates thereceiving holes 13 which form a defined starting point of the materialstrip 3 or of the divided material strip 3 a, 3 b.

FIG. 3 shows an alternative embodiment of the invention in which thefirst cutting device 1 makes a more complex cut of the first materialstrip 3. In this embodiment—aside from the longitudinal cut 12 whichruns lengthwise—during the first cut, the first cutting device 1 makes atransversal separating cut 14, a window cut 15, a two-part arrester cut16 as well as transport holes 17 into the first material strip 3. Forthis purpose, it is merely necessary for the rotary blades 11 arrangedin the bottom roller 4 to be designed with an appropriate cuttingcontour.

In this context, it is important for the edge 10 not to be completelysevered anywhere in the transversal direction. Only by retaining acontinuous connection can the edge 10 fulfill its function as atransport section 18 and can it absorb and transmit tensile forces inthe lengthwise direction of the first material strip 3. Such transportforces can be transmitted to the transport section 18, for example, bymeans of rollers. As an alternative, however, mechanical elements canalso engage with the transport holes 17, thereby conveying the firstmaterial strip 3 continuously, quickly and without interruptions andwith a high level of precision.

Furthermore, the windows 19 created by means of the window cuts 15 aresignificant for the invention since strips of material situatedunderneath or above them can be cut through these windows 22.

The separating cut 14 that has already been made in this place is madein the lengthwise direction 20 at a distance of X+Δ₁. This means thatthe anode 7 that is finished later will have a length of X+Δ₁.Accordingly, a width 21 of the anode 7 will have a measurement of Y+Δ₁,which corresponds essentially to the width of the inside section of thearrester cut 16, which is at a distance from the edge 10. The twotransversal sections of the arrester cuts 16 that are arranged next toeach other in a transport section 18 already define the width of anarrester 25 of the electrode that is to be created later and that, inthis case, is an anode 7. Whereas the receiving holes 13 are only neededwhen a material strip 3 is positioned for the first time, the transportholes 17 can be used continuously, that is to say, during the entireproduction process, in order to transmit drive forces as well as toprecisely position the material strip 3.

FIG. 4 shows a second material strip 22 that undergoes a first cut thatessentially corresponds to the cut illustrated in FIG. 3. The differencein the embodiment shown in this figure is that this is a cathode 23. Forthis purpose, the second material strip 22 is initially fed to the firstcutting device 1 from a second supply means 26. In this context, it isparticularly efficient if several first cutting devices are employed inparallel in order to simultaneously make the first cut into the firstmaterial strips 3 of anodes 7 and into the second material strips 22 ofcathodes 23.

In order to be used as cathode 23, the transport section 18 with itsedge 10 and a cathode area 24 are made of appropriate materials that aresuitable for the cathode 23 of a battery cell 8. For this purpose, forinstance, an aluminum substrate can be employed as the support for acathode active material. Another difference from the anode 7 is that thelength of the cathode 23 in the lengthwise direction 20 and its width 21are slightly smaller than the length in the lengthwise direction 20 andthe width 21 of the anode 7 shown in FIG. 3. In the embodiments shown,the anode 7 is larger than the cathode 23 by the differential dimensionAi. This applies to the lengthwise direction 20 as well as to thedirection of the width 21.

The separate second material strips 22 a, 22 b resulting from the firstcut can then be further processed directly and separately from eachother.

FIG. 5 shows another first cutting device 1 to which a third strip ofmaterial 27 is fed from a third supply means 28. The third strip ofmaterial 27 is a separator 29 that has insulating properties and that issuitable for electrically insulating anodes 7 and cathodes 23 from eachother. The third strip of material 27, in turn, undergoes a first cutusing a bottom roller 4 and a top roller 5. A perforating unit 6 islikewise provided in order to create receiving holes 13.

The upper area of FIG. 6 shows a view from below of the bottom roller 4,whereby the perforating unit 6 is not depicted. In this embodiment, thebottom roller 4 has a rotary blade 11 that is configured to maketransversal separating cuts 14 at defined places of the third strip ofmaterial 27, whereby, however, these separating cuts 14 do not extendover the entire width of the third strip of material 27, but rather,they skip an edge 10. As a result, transport sections 18 that can absorbtensile forces are created in the edge 10 on both sides of the thirdstrip of material 27, thus allowing further mechanical processing of thethird strip of material 27 in the continuous, uncut state. Moreover, theperforating unit 6 not shown in this figure creates receiving holes 13in the third strip of material 27.

The lower area of FIG. 6 shows a variant in which the third strip ofmaterial 27 is twice as wide as the width of the separator 29 needed forthe battery cell 8. In this case, the bottom roller 4 can be configured,for example, in such a way that, in addition to the transversalseparating cut 14, it also makes a lengthwise longitudinal cut 12 andcuts the third strip of material 27 into two halves in its length. Forpurposes of attaining safe operation of a battery cell 8, it isadvantageous for the separator 29 to be larger than the anode 7 orcathode 23 that is to be insulated. For this reason, starting with theabove-mentioned basic dimensions X and Y of the cathode 23, theseparator 29 is cut to a width of Y+Δ₂ and to a length of X+Δ₂. In thiscontext, λ₂ constitutes the oversize by which the separator 29 issupposed to be larger than the cathode 23.

FIG. 7 shows four strips of material that are combined on top each otherto form a partial stack. As seen from the bottom to the top, thisconsists of an anode 7, a separator 29, a cathode 23 and anotherseparator 29. In the state shown, all of the strips of material havealready undergone a first cut.

FIG. 8 shows the subsequent method step in a side view. As seen comingfrom the left-hand side and in the state after the first cut, a firstmaterial strip 3, a second material strip 22 as well as two third stripsof material 27 are fed in such a way that a third strip of material 27is arranged between the first material strip 3 and the second materialstrip 22, while another third strip of material is situated on top ofthe second material strip 22. In this process, the four material strips3, 27, 22 are combined by means of guide means 30 to form a partialstack 31. Here, a first clamping apparatus 32 engages with theright-hand end of the partial stack 31 while a second clamping apparatus33 engages with the left-hand end of the partial stack 31. The mode ofoperation of the clamping apparatuses 32 and 33 will be elaborated uponbelow. The further transport of the partial stack 31 in the lengthwisedirection 20 is carried out by transport pins 34 that engage with thetransport holes 17 of the first material strip 3 and of the secondmaterial strip 22. The transport pins 34 are driven by a drive means notshown here and they exert a drive force onto the appertaining transportsection 18. For the initial placement of a strip of material, there arealso receiving pins 35 that engage with the receiving holes 13 and thatare coordinated in such a way that the strip of material that is to benewly put in place and its cut contour stemming from the first cut areprecisely fed in a defined position. Over the further course, this isfollowed by a cam drive 36 which, on the one hand, is configured todrive the transport pins 34 or the receiving pins 35 and, on the otherhand, to allow a smooth passage through the first clamping apparatus 32and through the second clamping apparatus 33 so as to reach the positionsituated further to the right, where a third clamping apparatus 37 isthen placed against the partial stack 31.

FIG. 9 shows the partial stack 31 of FIG. 8 once again in a top view.The first clamping apparatus 31 and the second clamping apparatus 33 canbe clearly seen here. In this context, it can also be clearly seen thatthe transport sections 18 of the anode 7, of the cathode 23 and of theseparators 29 are arranged offset in the transversal direction, that isto say, in the crosswise direction. In particular, this causes thetransport section 18 of the separators 29 to be located in the anode 7or in the cathode 23 completely inside the windows 19. In order toalways ensure a correct transversal orientation of the strips ofmaterial, a monitoring instrument 38 is provided which can beconfigured, for instance, as a position detector or as an opticalstrip-edge regulator for controlling the width of the separator 29.

FIG. 10 shows the first clamping apparatus 32 in a sectional view in thelengthwise direction 20 of the partial stack 31. When the clampingapparatus 31 is put in place, two grippers 39 are brought into positionabove and below the partial stack 31.

FIG. 11 then shows the first clamping apparatus 32 in a closed state inwhich the grippers 39 are to be moved towards each other, thereby firmlyclamping the partial stack 31 in this process. This ensures that nomovement of the material strips 3, 22, 27 relative to each other canoccur during the subsequent processing.

FIG. 12 shows the second clamping apparatus 33 in an open state on theleft-hand side, and in a closed state on the right-hand side. When thesecond clamping apparatus 33 is put in place, several grippers 39 areinserted from the side between the material strips 3, 22, 27. Once thishas taken place, the grippers 39 are, in turn, moved towards each otherin order to close the second clamping apparatus 33.

As can be seen in FIG. 13, the grippers 39 in this embodiment of thesecond clamping apparatus 33 are configured differently. For instance,there are grippers 39 with a round cross section and grippers 39 with arectangular cross section. When the grippers 39 are then moved towardseach other, the round grippers 39 are surrounded to an increasing degreeby the strip of material that is between them; in this case, these arethe two strips of material 27 of the separators 29. As a result, theeffect occurs that the additional path length of the third strips ofmaterial 27 needed to surround the grippers is replenished from theoutside. When the first clamping apparatus 32 is then closed, followedby the second clamping apparatus 33, then the loose end of the thirdstrip of material 27, which is at the rear left-hand side of the partialstack 31, is replenished in the lengthwise direction 20, and thus pulledto the front or to the right as seen in the plane of the drawing.

FIG. 14 shows the partial stack 31 with the replenished separators 29 asthey pass through the cam drive 36. In this context, the transport pin34 is extended and engages with an opposite cam wheel 40 and with thepartial stack 31. The rotation of the two cam wheels 40 of the cam drive36 causes the partial stack 31 to be conveyed further in the lengthwisedirection 20. A second transportation pin 34 is shown in the upper camwheel 40 in a retracted state and it is not yet engaged with the partialstack 31.

FIG. 15 shows a cam wheel 40 of a cam drive 36 in a sectional view. Thecam wheel 40 has extendable transport pins 32 and recesses 41. Whereasthe transport pins 34 serve to engage with the transport holes 17 of thestrips of material, the recesses 41 serve to allow the first clampingapparatus 32 and the second clamping apparatus 33 to pass through thecam wheel 34 without any problems. Extending or retracting the transportpins 34 can be controlled particularly easily by means of a cam track 42in that a plate 43 that is connected to the transport pins 34 is pressedagainst the cam track 42 by means of springs 44. In this context, thecam track 42 is configured in such a way that the transport pins 34 areextended precisely at the time when they can engage with a transporthole 17 during the course of the rotational movement of the cam wheel40.

FIG. 16 shows a top view and a side view of the partial stack 31 as itpasses through the cam drive 36. Here, the first clamping apparatus 32and the second clamping apparatus 33 have been put in place. Thetransversal separating cut 18 [sic] into the separators 29 is shown hereonce with a broken line and once with a solid line. The broken linedepicts the position of the separating cut 18 [sic] before the firstclamping apparatus 32 and the second clamping apparatus 33 have been putin place. In this process, the first clamping apparatus 32 was put inplace first and subsequently the second clamping apparatus 33. As aresult, the additionally needed path length of the separators 29 whenthe second clamping apparatus 33 was put in place can only bereplenished from the left-hand side, that is to say, from the thirdsupply means 28. In accordance with this additionally replenished pathlength, the separating cut 18 [sic] indicated by the broken line hasmigrated to the right into the position of the separating cut 18 [sic]indicated by the solid line. This means that, during a continuousproduction process, a longer length of the third strip of material 27 isdispensed than the lengths of the first material strip 3 and of thesecond material strip 22 that have been dispensed by the first supplymeans 2 and by the second supply means 26. As a result, it is possiblethat, in its finished state, the separator 29 protrudes beyond the anode7 and the cathode 23 not only in the transversal direction, but rather,also beyond them in the lengthwise direction 20, thus ensuring safe andreliable insulation. The lower area of FIG. 16 once again shows a sideview of this section presented above. It can be clearly seen here howthe second clamping apparatus 33 in its placed state increases the pathlengths of the separators 29. This view also clearly shows that thetransport sections 18 of the three material strips 3, 22, 27 arearranged so as to be clearly separated from each other in thetransversal direction. Moreover, here too, the transport section 18 ofthe separators 29 is arranged so far towards the inside, that is to say,away from the edge 10, that it is inside the window 19. The laterallyoffset—in other words, offset in the transversal direction—arrangementof the transport sections 18 has several advantages in this respect. Forinstance, the transport pins 34 can engage on one side with thetransport holes 17 of the anode 7 as well as with the transport holes 17of the cathode 22 on the opposite side. Consequently, both materialstrips 3, 22 can be driven synchronously in that the drive forcesnecessary for this purpose, which are normally introduced into amaterial strip 3, 22, 27 as tensile forces, are transmitted to thematerial strips 3, 22.

Another advantage of the laterally offset arrangement of the transportsections 18 can be achieved if the transport section 18 of a materialstrip 3, 22, 27 such as, for example, the transport section 18 of theseparator 29, is arranged in such a way that it is above at least onewindow 19 of the adjacent material strips 3, 22, such as, for instance,of the anode 7 or of the cathode 23. In this embodiment, the separator29 can be cut at any desired place inside the window 19. To put it moreprecisely, towards this end, the transport section 18 of the separatoris severed in the transversal direction at this position, which isfreely selectable inside the window 19. For this purpose, it is merelynecessary for the separating cut 14 that has been made in the separator29 by the first cutting device 1 to be appropriately positioned insidethe window 19. Once this has been done, as shown in the figure, then thetransport section 18 that is still present in the separator can besevered transversally very easily in that the separating cut 18 [sic] islengthened all the way to the side edge of the separator 29. This can bedone very easily by means of a second cutting device 45 which isconfigured, for instance, as a roller punching device or as a rollercutting device. Within the scope of this second cut, it is thenespecially possible to make additional cuts such as, for example,exposing the arresters 25 by lengthening the arrester cut 16 all the wayto the edge, or else by severing the lateral transport sections 18 fromthe anode 7 and from the cathode 23 by means of a cut in the lengthwisedirection of the partial stack 31.

FIG. 17 shows a second cutting device 45 in a top view. This secondcutting device 45 makes a second cut is made in which the partial stack31 is then also cut open in the transversal direction. In this context,the transport sections 18 that had been used until this point in timeare then cut off. In the state shown here, the partial stack 31 issimultaneously held by the first, second and third clamping apparatuses32, 33, 37, not shown here. In this context, owing to the placement ofthe second clamping apparatus 33, the separating cut 14 is shifted tothe right, from the initial position indicated by the broken line to theposition indicated by the solid line.

The second cutting device 45 has a first roller 46 and a second roller47, both of which interact with a counter roller 48. In this process,the first roller 46 cuts the anode 7 and one side of the separators 29.The second roller 47 cuts the cathode 23 and the other side of theseparators 29. The separators 29 are cut in that the separating cut 14through the separator 29 is transversally lengthened in the area of thewindow 19, so that individual separators 29 that have now been dividedin the lengthwise direction are formed from the continuous separators29. Only now can the separator 29 be cut through the window 19separately from the electrodes.

Moreover, the anode 7 and the cathode 23 undergo the final cut in thatthe appertaining arrester cuts 16 from the first roller 46 or from thesecond roller 47 are either lengthened transversally outwards to theedge 10 or else severed by means of a longitudinal cut running in thelengthwise direction. Ribbons 49 are then cut off by the longitudinalcut. Both cuts, that is to say, in the transversal direction and in thelongitudinal direction, can also be made simultaneously.

FIG. 18 shows the first roller 46 in an enlarged view. The roller 46here has recesses 41 so that the first and second clamping apparatusescan pass through them without any problem. Moreover, there are separatorblades 50 for lengthening the separating cuts 14 in the separators 29,and arrester blades 50 for lengthening the arrester cuts 16.Furthermore, a radially arranged blade can be provided on one of therollers 46, 47, 48 in order to cut off the ribbons 49 in the same workstep.

FIG. 19 once again shows the first roller 46 together with the counterroller 48, between which there is a partial stack 31. The counter roller48 as well as the first roller 46 have recesses 41 in order to ensureeasy passage of the first clamping apparatus 32 and of the secondclamping apparatus 33. Moreover, the first roller 46 has transport pins34 that engage with the transport sections 18 of the anode 7 or of thecathode 23 and that ensure reliable transport as long as the transportsections 18 have not yet been cut off. In order to make the second cut,the first roller 46 has a separator blade 50 and two arrester blades 51with which the separating cut 14 in the separators 29 can be lengthenedand the arresters 25 can be exposed.

FIG. 20 shows a top view of the second cutting device 45. Here, as seenfrom left to right, initially the third clamping apparatus 37 isactivated simultaneously with the first clamping apparatus 32 and withthe second clamping apparatus 33. Over the further course of themovement of the partial stack 31 towards the right, then the secondclamping apparatus 33 and subsequently the first clamping apparatus 32are opened, so that the replenished separators 29 can move from thesurrounded position in the second clamping apparatus 33 back to a flatposition and parallel to the anode 7 or the cathode 22. In this process,the separating cuts 14—located in the rear as seen in the lengthwisedirection 20—that were made to create the separators 29 move away fromthe appertaining arresters 25, thereby reliably protruding beyond theanode 7 or the cathode 22, also in the lengthwise direction.

After the first clamping apparatus 32 and the second clamping apparatus33 have been opened, they are then moved by conveyor belts 52 back totheir initial position where they can once again be placed against apartial stack 31. At the same time, gripping means 53 are placed againstthe partial stacks 31 so that these can be further transported tomagazines 54 and stacked there once the third clamping apparatus 37 hasbeen opened. Like the clamping apparatuses 32, 33 and 37, the grippingmeans 53 also work in one recurring process in order to allow a fast andcontinuous production of the cell stacks 57.

FIG. 21 shows the third clamping apparatus 37 in a side view. The thirdclamping apparatus 37 likewise has a plurality of clamping elements 55that are attached to a second conveyor belt 56, whereby the secondconveyor belt 56 moves at the same speed as the speed with which thepartial stack 31 is being transferred by the first clamping apparatus 32and by the second clamping apparatus 33. After the transfer of thepartial stack 31 to the gripping means 53, the clamping elements 55 arethen moved downwards or upwards and then once again moved to the left ina counter movement, where they are then once again placed onto the nextpartial stack 31. As the next step, the gripping means 53 feed thepartial stack 53 to a magazine 54 where several partial stacks 31 arestacked on top of each other in order to form a cell stack 57.

Since the partial stacks 31 consist of four strips of material whichcomprise an anode 7, a separator 29, a cathode 22 and another separator29 and which are arranged on top of each other from the bottom to thetop in this sequence, first of all, a single separator 29 is insertedinto the empty magazine 54. This single separator 29 serves to preventthe anode 7 that is at the bottom on the partial stack 31 from makingelectric contact with other components. Towards this end, a supply ofindividual separators 29 is kept ready on the magazine 54 in areceptacle 58. In this context, every time an empty magazine 54 is aboutto be filled, a feeding means 59 uses, for example, a vacuum liftingtool to place a separator 29 into the magazine 54 as the first strip ofmaterial. Once the cell stack 57 is complete, the magazine 54 is movedand replaced by another empty magazine 54. While this second magazine 54is being filled, the cell stack 57 in the first magazine 54 can be boundto form a cell packet 60 and can subsequently be taken away. At higherproduction speeds, it is also possible to employ several magazines 54.Towards this end, for instance, two additional magazines 54 can beprovided which are arranged parallel to the first two magazines andwhich can be filled with partial stacks 31 by means of gripping means 53that have a greater range. In this context, when the additionalmagazines 54 are in the empty state, they can be replenished with aseparator 29 by the feeding means 59. This allows the production toproceed without interruptions and at a high speed.

On the left-hand side, FIG. 22 shows a top view of a filled magazine 54,comprising a cell stack 57 above a conveyor belt 61. To the right of it,a finished cell packet 60 that is ready to be taken away is shown on theconveyor belt 61. Pushers 62 serve to bind the cell stack 57 with anadhesive tape 63 in order to form a firm cell packet 60. In thiscontext, the end faces 64 of the cell stack 57 are held inside themagazine 54 where the arresters 25 are also located.

FIG. 23 illustrates the first step in the gluing operation. In thiscontext, the pushers 62 are initially moved sideways to the outside andfour adhesive tapes 63 are pulled from adhesive tape rolls 66 by meansof adhesive pull tabs 65.

FIG. 24 shows the second step in which the pushers 62 are moved up tothe cell stack 57 and they then press the adhesive tape 63 against thecell stack 57 from the side. In this process, the adhesive tapes 63 aresimultaneously cut by blades 67 that are arranged on the pushers 62.During the cutting procedure, the adhesive pull tabs 65 at the same timefunction as counter supports for the blades 67.

FIG. 25 shows how the pushers 62 are subsequently moved further in thedirection of the cell stack 57 and, in this process, they press the cutadhesive tapes 63 onto the cell stack 57 so that a cell packet 60 isformed.

Subsequently, as shown in FIG. 26, the cell packet 60 thus formed isplaced onto the transport belt 61 and taken away.

FIG. 27 shows how a bottom 71 of the magazine 54 then opens by beingswiveled away downwards, after which the pushers 62 place the cellpacket 60 onto the transport belt 61.

FIG. 28 shows a finished cell packet 60 with the arresters 25 and thesurrounding adhesive tape 63.

Finally, FIG. 29 shows an alternative embodiment that can perform thefunction of a first and a second clamping apparatus 32, 33 as well as ofa second cutting device 45. Depicted here is a partial stack 31 that hasalready passed through a first cutting device 1 and is now beingtransported by the cam drive 36 to the second cutting device 45. In thisprocess, a bottom roller 4 is used that can be configured, for example,as a cam-driven counter roller having a shaping stamp 68 made of rubber.Here, the shaping stamp 68 is configured in such a way that, when aseparating cut 14 of a separator 29 enters the second cutting device 45,the partial stack 31 is forced into a curved movement trajectory 69 overthe approximately elliptical, not circular, shaping stamp 68. Thecurvature generated in this process is once again reinforced in that, inthis position, the shaping stamp 68 is additionally deformed by a pin 70in the direction of the partial stack 31. As a result, the materialstrips 3, 22, 27 can be bent, a procedure which, in this state, alsobrings about a shifting of these material strips 3, 22, 27 relative toeach other. If the separators 29 in this position are then severed bymeans of the separator blade 50 arranged on the top roller 5, then aseparator 29 is obtained that is longer than the anode 7 or cathode 23situated underneath it. Subsequently, the arrester cuts 16 can be madeby means of the following arrester blades 51, whereby the partial stack31 does not undergo any curvature in this rotational position of the toproller 5 and of the bottom roller 4 since, in this subsequent rotaryposition, the shaping stamp 68 is not positioned against the partialstack 31. This means that the arrester cuts 16 are made by means of thearrester blades 51 on a straight and elongated partial stack 31.

The present invention allows four works steps to be carried out in oneinstallation. These work steps consist of the longitudinal cutting, thecrosswise cutting, the stacking and the gluing or taping of the cellstacks.

Moreover, very high stacking speeds can be attained, whereby thepreferably four strips of material are continuously secured by aclamping apparatus 32, 33, 37 or by a gripping means 53, whichtranslates into very high positioning and manufacturing accuracy.

The strips of material do not have to first be individuated and thenjoined again, as a result of which very little material handling isneeded and very good material utilization is achieved in comparison to,for example, accordion folding.

Owing to the high positioning accuracy, it is also possible to reliablyensure the oversize of, for instance, 6 mm, that is needed for theseparator 29 vis-à-vis the cathode 23.

Finally, otherwise customary lamination processes can be dispensed with,as a result of which there is no need to use expensivelamination-capable separators 29.

LIST OF REFERENCE NUMERALS

-   -   1 first cutting device    -   2 first supply means    -   3 first strip of material    -   3 a, 3 b divided first strip of material    -   4 bottom roller    -   5 top roller    -   6 perforating unit    -   7 anode    -   8 battery cell    -   9 anode area    -   10 edge    -   11 rotary blade    -   12 longitudinal cut    -   13 receiving holes    -   14 separating cut    -   15 window cut    -   16 arrester cut    -   17 transport hole    -   18 transport section    -   19 window    -   20 lengthwise direction    -   21 width    -   22 second strip of material    -   22 a, 22 b divided second strip of material    -   23 cathode    -   24 cathode area    -   25 arrester    -   26 second supply means    -   27 third strip of material    -   28 third supply means    -   29 separator    -   30 guide means    -   31 partial stack    -   32 first clamping apparatus    -   33 second clamping apparatus    -   34 transport pin    -   35 receiving pin    -   36 cam drive    -   37 third clamping apparatus    -   38 monitoring instrument    -   39 gripper    -   40 cam wheel    -   41 recess    -   42 cam track    -   43 plate    -   44 spring    -   45 second cutting device    -   46 first roller    -   47 second roller    -   48 counter roller    -   49 ribbon    -   50 separator blade    -   51 arrester blade    -   52 conveyor belt    -   53 gripping means    -   54 magazine    -   55 clamping element    -   56 second conveyor belt    -   57 cell stack    -   58 receptacle    -   50 feeding means    -   60 cell packet    -   61 transport belt    -   62 pusher    -   63 adhesive tape    -   64 end face    -   65 adhesive pull tabs    -   66 adhesive tape roll    -   67 blade    -   68 shaping stamp    -   69 movement trajectory    -   70 pin    -   71 bottom

1. A method for producing a cell stack for battery cells, said methodcomprising at least the following steps: feeding in at least a firstmaterial strip consisting of a first material; making a first cut intoat least the first material strip while forming at least one transportsection having tensile strength; combining the first material strip withat least a second material strip consisting of a second material, so asto form a partial stack; making a second cut of the partial stack,whereby the transport section is cut open; and arranging at least twopartial stacks so as to form a cell stack.
 2. The method according toclaim 1, whereby the first material strip and the second material strip(are cut to different dimensions.
 3. The method according to claim 1,whereby during the cut, a transport engagement means or a window sectionis created in the material strip, especially in the transport section.4. The method according to claim 1, whereby the partial stacks consistof at least four material strips.
 5. The method according to claim 1,whereby arrester lugs are formed on at least two material strips duringthe cutting.
 6. The method according to claim 1, whereby the cell stackis joined to form a cell packet using a joining means.
 7. The methodaccording to claim 1, whereby at least one additional material strip isarranged in the cell stack while the partial packets are being arrangedto form the cell stack.
 8. A battery cell having a cell stack, producedaccording to claim
 1. 9. A motor vehicle having at least one batterycell according to claim
 8. 10. A device for producing a cell stack,comprising: at least two supply means for at least a first materialstrip and a second material strip, at least a first cutting device and asecond cutting device for cutting the material, a transport means forconveying the material strips, an apparatus for combining the materialstrips, and a stacking unit, whereby, on each material strip, the firstcutting device creates at least one transport section having tensilestrength, whereby the second cutting device is arranged in a lengthwisedirection downstream from the apparatus for combining the materialstrips, and said second cutting device is configured to make acompletely transversal separation of the material strips.
 11. The deviceaccording to claim 10, wherein the first cutting device is configured toundertake parallel cutting of at least two material strips.
 12. Thedevice according to claim 10, wherein the first cutting device isconfigured to cut at least one material strip parallel to the lengthwisedirection in a plurality of material strips.